Przyimki czasu / in time/ on time

Wynika to z określenia dokładności czasu:
1. on time - oznacza dokładnie na czas, punktualnie.

LDOCE:
at the correct time or the time that was arranged :
/Jack was worried about whether he’d be able to get there on time./
right/bang/dead on time (= at exactly the right time )
/The plane arrived right on time./

2. in time - oznacza nieco przed czasem, w samą porę

LDOCE:

a) before the time by which it is necessary for something to be done :
/Will you be able to finish it in time? /
in time to do something
/They ran all the way to the corner just in time to see the bus disappearing up the street./
in time for
/The painting was successfully repaired in time for the opening of the exhibition./
in good time/in plenty of time (= a long time before the necessary time )
/We arrived at the concert hall in good time./
b) after a certain period of time, especially after a gradual process of change and development :
/He wants to see changes in the company and I am sure he will, in time./

Odpowiedź na Pani pytanie znajduje się w wątku:

https://www.etutor.pl/pytania-jezykowe/pytanie/18829-on_time_in_time.html